The present invention relates to an internal combustion engine breather apparatus and in particular an improved apparatus for introducing internal combustion engine breather gases into the exhaust gas stream of an internal combustion engine.
In an internal combustion engine such as a diesel engine, the pressure differential above and below the piston causes a small amount of gas leakage from the combustion chamber past the piston and into the crankcase. The pressure rise thus brought about in the crankcase can lead to oil being forced past the crankcase oil seals and causing other similarly undesirable effects.
It is known to maintain a relatively constant and low level of crankcase pressure by connecting the crankcase to the environment via an open breather through which gas may pass. However, there are disadvantages to open breathers in that oil droplets may coalesce and drip form the breather, thus contravening environmental regulations or expectations in respect of fluid leakage from machines. Further, gas pressure pulsation may cause dust from the local environment to be drawn into the engine.
To overcome the above-mentioned problems, it is known to provide closed circuit breather systems in which the breather gas is fed into the intake air of the engine for subsequent combustion. However, some of the oil carried with the breather gas will carbonise upon contact with hot engine components such as turbocharger compressors and intake air intercoolers and thus impede air flow. To reduce this problem, gas/oil separators are often employed but these add cost to the engine and do not totally remove the oil content of the breather gas, particularly where this is in the form of a fine aerosol rather than sizeable droplets.
A further problem with closed circuit breathers connected to the engine air intake system concerns the risk of oil carryover into the air intake system in such quantity that the engine may become fueled by the oil and engine run-away (uncontrolled engine acceleration) may hence occur.
In an effort to overcome one or more of the above-mentioned problems, it has been proposed in the prior art (for example, patents GB 1531080 and DE 3312818) to feed the breather gas into the exhaust system of the engine. A disadvantage of feeding the breather gas into the exhaust before the muffler, or silencer, is that a device such as a venturi will be needed to reduce the pressure in the exhaust pipe at the point of entry of the breather gas, such that the resultant pressure in the crankcase remains at a relatively constant and low level. The prior art generally either discloses passing the breather gas into the exhaust at a point relatively close to the engine or is silent regarding the point in the exhaust at which the breather gas enters. An exception is Japanese unexamined patent application 8-61037 which proposes that the breather gas be introduced into the exhaust system at a point downstream of the muffler. However, the apparatus disclosed within JP 8-61037 has severe disadvantages as are described forthwith.
In JP 8-61037, the breather pipe outlet passes through the wall of the muffler tailpipe and is contained largely within the tailpipe in the flow of the exhaust gas stream. The mass flow of exhaust gas will be far higher than the mass flow of breather gas, hence the breather pipe outlet will be at, or very close to, the exhaust gas temperature which can range up to 560xc2x0 C. in the tailpipe of a turbocharged diesel engine exhaust system. Lubricating oil carbonizes at around 180-200xc2x0 C., therefore a significant proportion of the oil carried within the breather gas during its passage through the breather pipe outlet will carbonize and this will very quickly block the outlet and cause an unacceptably high crankcase pressure. Frequent and possibly difficult decarbonization will thus be needed.
Further, an apparatus constructed in accordance with JP 8-61037, with the breather pipe outlet normal to the wall of the tailpipe but formed with a bend, will not only severely exacerbate the carbonization and subsequent decarbonizing problems but will prove relatively expensive to manufacture and install.
The present invention is directed to overcoming one or more of the problems set forth above.
In one aspect of the present invention, a breather gas outlet for an internal combustion engine having an exhaust system is provided. The exhaust system has a wall and an aperture disposed in the wall. The breather breather gas outlet has an adaptor with a hollow member. The hollow member has a first end adapted to engage in the aperture of the wall of the exhaust system and provide a breather gas communication into the exhaust system. A nozzle having a second hollow member to serve as a breather gas passage is positioned inside the adaptor. The nozzle has a mounting portion sealingly engaging with an inside surface of the adaptor towards a second end of the adaptor. A nozzle portion extends laterally towards and ending short of the first end of the adaptor. The nozzle portion has an outer dimension less than an inner dimension of the adaptor and defining a space therebetween.
In another aspect of the present invention, an exhaust system is provided with a wall and an aperture disposed in the wall. A breather gas outlet is engaged with the wall of the exhaust system and delivers breather gas communication into the exhaust system. The breather gas outlet has an adaptor and a nozzle. The adaptor has a hollow member with a first end adapted to engage in the aperture of the wall of the exhaust system and deliver the breather gas communication into the exhaust system. The nozzle has a second hollow member serving as a breather gas passage and is positioned inside the adaptor. The nozzle has a mounting portion sealingly engaging with an inside surface of the adaptor towards a second end of the adaptor and a nozzle portion extending laterally towards but ending short of the first end of the adaptor. The nozzle portion has an outer dimension less than an inner dimension of the adaptor and defining a space therebetween.
In yet another aspect of the present invention, a breather system has a breather gas outlet and a breather gas conduit adapted to be connected to a crankcase of and internal combustion engine. An exhaust system is adapted to being connected to the internal combustion engine. The exhaust system has a wall and an aperture disposed in the wall. The breather gas outlet is engaged with the wall of the exhaust system and delivers breather gas flow into the exhaust system. The breather gas outlet has an adaptor and a nozzle. The adaptor has a hollow member with a first a first end adapted to engage in the aperture of the wall of the exhaust system and deliver the breather gas into said exhaust system. The nozzle has a second hollow member serving as a breather gas passage which is positioned inside the adaptor. The nozzle has a mounting portion sealingly engaging with an inside surface of the adaptor towards a second end of the adaptor and a nozzle portion extending laterally towards but ending short of the first end of the adaptor. The nozzle portion has an outer dimension less than an inner dimension of the adaptor and defining a space therebetween.
In yet another aspect of the present invention, there is provided a method of fitting a breather gas outlet to an engine exhaust. The method includes the steps of: providing a hollow nozzle member at a downstream end of a breather gas conduit; mounting the nozzle inside a hollow adaptor member, by sealingly engaging a mounting portion of the nozzle with an inside surface of the adaptor, such that a nozzle portion of the nozzle extends laterally towards but ends short of a downstream end of the adaptor, the nozzle portion having an outer dimension less than the inner dimension of the adaptor so as to form a space therebetween; and engaging the downstream end of the adaptor at an aperture in a wall of an exhaust system of an engine to provide a breather gas communication thereinto.